Which epidural dose of bupivacaine will give similar sensory analgesia as 10 mL of 2% lidocaine?

Which epidural dose of bupivacaine will give similar sensory analgesia as 10 mL of 2% lidocaine?

• A. 5 mL of 0.25%
• B. 10 mL of 0.25%
• C. 5 mL of 0.5%
• D. 10 mL of 0.5%

Answer: (D)

Bupivacaine is much more potent than lidocaine, so a smaller amount of bupivacaine is needed to achieve the same sensory analgesia in the epidural space. If 10 mL of lidocaine 2% provides 200 mg, an equianalgesic amount of bupivacaine is roughly one-quarter of that mass—about 50 mg—because of the greater potency of bupivacaine. Ten milliliters of a 0.5% solution delivers 50 mg (0.5% equals 5 mg/mL; 5 mg/mL × 10 mL = 50 mg). The other options supply far less than 50 mg (for example, 5 mL of 0.5% is 25 mg; 10 mL of 0.25% is 25 mg; 5 mL of 0.25% is 12.5 mg). Hence, 10 mL of 0.5% bupivacaine best matches the sensory analgesia produced by 10 mL of lidocaine 2%.

Bupivacaine is much more potent than lidocaine, so a smaller amount of bupivacaine is needed to achieve the same sensory analgesia in the epidural space. If 10 mL of lidocaine 2% provides 200 mg, an equianalgesic amount of bupivacaine is roughly one-quarter of that mass—about 50 mg—because of the greater potency of bupivacaine.

Ten milliliters of a 0.5% solution delivers 50 mg (0.5% equals 5 mg/mL; 5 mg/mL × 10 mL = 50 mg). The other options supply far less than 50 mg (for example, 5 mL of 0.5% is 25 mg; 10 mL of 0.25% is 25 mg; 5 mL of 0.25% is 12.5 mg). Hence, 10 mL of 0.5% bupivacaine best matches the sensory analgesia produced by 10 mL of lidocaine 2%.